1. Field of the Invention
The present invention relates to a device and a method used in a wireless communication system, and more particularly, to a device and a method of handling system information.
2. Description of the Prior Art
A long-term evolution (LTE) system provides high data rate, low latency, packet optimization, and improved system capacity and improved coverage. The LTE system is evolved continuously to increase peak data rate and throughput by using advanced techniques, such as carrier aggregation (CA), dual connectivity, licensed-assisted access, etc. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes at least one evolved Node-B (eNB) for communicating with at least one user equipment (UE), and for communicating with a core network. The core network may include a mobility management and a Quality of Service (QoS) control of the at least one UE.
The eNB may move a UE to a RRC_IDLE state, if the eNB determines that the UE needs to acquire changed system information. However, there is no mechanism for the UE to check if it already has (or obtains) up-to-date system information, before the UE initiates a connection establishment procedure. According to the prior art, the UE obtains system information just enough for entering a RRC_CONNECTED mode. In this situation, the UE may initiate the connection establishment procedure before acquiring all changed system information, and the connection establishment procedure may be failed. Accordingly, the eNB may release the UE to ask the UE to acquire the changed system information. Again, the UE may not obtain all the changed system information, i.e., a deadlock is caused to the interaction between the eNB and the UE. Thus, how the UE handles the system information is an important to be solved.